Circuit breaker



Nov. 12, 1957 E. T. EBERHARD ETAL 2,813,177

' CIRCUIT BREAKER Filed March 29, 1954 2 Sheets-SheeI l fire: z

United States Patent O CIRCUIT BREAKER Eimer T. Eberhard, Pacoma, andEyvind Eklnnd, Temple City, Calif., assignors to Kalman Electric andManufacturing Company, Los Angeles, Calif., a corporation of CaliforniaApplication March 29, 1954, Serial No. 419,218

7 Claims. (Cl. 200-150) The present invention relates in general tocircuit breakers and, more particularly, to a high-voltage circuitbreaker of the type wherein the contacts are immersed in oil, or othersuitable dielectric fluid, to extinguish or quench any arc formed uponbreaking of the contacts, jets of oil frequently being directed at thecontacts in circuit breakers of this type upon breaking of the contactsto aid in quenching or extinguishing any arc. However, while the presentinvention is particularly applicable to circuit breakers of this type,it will be understood that various features thereof are applicable tocircuit breakers of other types.

Conventional circuit breakers employ complex linkage mechanisms toseparate the contacts at a high rate of speed so as to minimize arcing,a primary object of the present invention being to provide a circuitbreaker having means for separating the contacts at a high rate of speedwithout the use of such complex linkage mechanisms.

More particularly, a primary object of the invention is to provide aduid-operated means for maintaining the contacts in engagement, thefluid-operated means being reversible to break the contacts andoperating at a high rate of speed in reverse to separate the contacts ata high rate of speed so as to minimize arcing. A related object is toprovide control means for the fluid-operated means which is responsiveto the current through the circuit breaker.

Still more particularly, an object of the invention is to provide aHuid-operated means which includes a differential-area piston connectedto a movable contact or contacts of the circuit breaker, thediiferential-area piston having a small area facing in the direction ofcontactclosing movement of the piston and having a large area facing inthe opposite direction, whereby the piston maintains the contacts closedwhen the large and small areas of the piston are subjected to the sameoperating uid pressure.

Another object is to provide a control means which includes a controlvalve for connecting the large-area side of the piston to a dischargemeans, whereby the piston moves in the contact-opening direction tobreak the contacts.

An important object is to provide a source of operating fluid underpressure which includes a pump and an accumulator, the pump normallymaintaining the uid system under pressure and the accumulator supplyingfluid to the small-area side of the piston at a high rate uponconnection of the large-area side of the piston to the discharge meansso that quick opening of the contacts is assured, which is an importantfeature of the invention.

Another important object is to provide a discharge means for spentoperating fluid on the large-area side of the piston which leads to thecontacts so as to deliver a jet of oil, or other suitable dielectricfluid, to the contacts to extinguish or quench any arc formed betweenthe contacts upon separation thereof, the jet of Huid being produced bydisplacement of the spent operating fluid v2,813,177 Patented Nov. 12,1957 from the large-area side of the piston as it moves in thecontact-opening direction.

Another object is to provide means for producing a plurality of jets ofoil, or other dielectric fluid, which extend transversely of the path ofseparation of the contacts and which are spaced along such path so as toinsure quenching of the arc upon a relatively slight separation of thecontacts.

Another object is to provide a quenching chamber in which the contactsare immersed in oil, or other dielectric iiuid, a return conduit beingprovided to return the tluid from a level above the contacts to areservoir to which the intake side of the pump is connected.

The foregoing objects, advantages and features of the present invention,together with various other objects, advantages and features thereofwhich will become apparent, may be attained with the exemplaryembodiments of the invention which are illustrated in the accompanyingdrawings and which are described in detail hereinafter. Referring to thedrawings:

Fig. l is a semidiagrammatic view, partially in elevation and partiallyin section, of a circuit breaker which embodies the invention;

Fig. 2 is an enlarged sectional view duplicating a portion of Fig. l andillustrating a quenching means of the invention;

Fig. 3 is a sectional view taken along the arrowed line 3 3 of Fig. 2;and

Fig. 4 is a View similar to Fig. 2 but illustrating another embodimentof a quenching means of the invention.

Referring particularly to Fig. l of the drawings, the circuit breaker ofthe invention includes a housing 5 which serves as a base for tubularinsulator sections 6 and 7, an annular conductor S being clamped betweenthe insulator sections 6 and 7 and having a terminal 9 for connection toan external circuit. The insulator section 7 is closed at its upper endby a cap assembly 10 having a second terminal 11 for connection to theexternal circuit, the purpose of the circuit breaker being to break thisexternal circuit in the event of an overload. The terminal 11 iselectrically connected to a conductor 12 carried by the cap assemblyItl, the conductor 12 being connected by conducting bolts 13 to aconducting cap 14 on the upper end of and carrying a tubular insulator15 disposed within and spaced inwardly from the insulator section 7. Aconducting support 16 is carried by the annular conductor 8 as discussedpreviously.

Disposed within the upper end of the tubular insulator 15 in conductingrelation to the cap 14 is a stationary contact or contact means 17having the form of a socket which includes a plurality of ngers 1Sbiased inwardly by spring means 19 and 2i), the latter being disposedbetween the fingers 1S and an outer shell 21. The contact or socket 17is maintained in position by being provided with an annular flange 22seated in a recess in the upper end of the tubular insulator 15 andmaintained in such recess by the cap 14 on the tubular insulator 15.

Engageable with the stationary contact or socket 17 is a movable contactor plug 23 formed by the upper end of a rod 24 which extends through thesupport 16 and is suitably sealed relative thereto, as by an O-ring.Mounted on the rod are rollers 25 which make electrical contact withtracks 26 carried by the support 16 in electrical contact therewith, thesupport, in turn, making electrical contact with the annular conductor8.

Thus, as will be apparent, when the plug 23 is inserted into the socket17, the circuit between the terminals 9 and 11 is made, and when theplug 23 is withdrawn from the socket 17 by downward movement of the rod24, the circuit between these terminals is broken. Movement of the rod24 to make or break the contacts 17 and 23 is produced by afluid-operated means 30 of which the rod 24 forms a part, theduid-operated means 30 being considered in the following paragraphs. Thefluid-,operated means 3i) includes a cylinder 34 having therein a piston-35 'to which Vth'efiod 24'is connected, the rod 24 being referred t`oas apiston rod 'hereinafter. A seal between the cylinder 34and thepiston rod 24 is provided byan 0ring, or other suitable sealing means.The presence of the piston rod 24 provides the piston 35 with asmallarea 36 on one side thereof and a large area 37 on the oppositeside thereof, thereby making the piston 35 a differential-area one. Thesmall and large areas 36 and 37 respectively face in the directions oflcontact closing and contact opening movement so that, when thepressuresappliedto the areas 36 and 37 are equal,-the contacts A17 and23 areclosed, and, when the area 36 is'exposed to Vhigh pressure whilethe area 37 is exposed -to low pressure, contact opening movement of thepistonV 35 occurs.

Communicating with the cylinder 34 on the small-area side 'of the piston35 is a first conduit 41V and communicating with the cylinder on thelarge-area side of the pistonis a vsecond con-duit 42, the latterbeingcontrolled by a solenoid valve 43 which is connected to a suitablecontrol means 44. For example, the latter may actuate the solenoid valve43 in response to an overload inthe external circuit to which theterminals 9 and 11 are connected. Also, communicating with the solenoidvalve `43 are a supply conduit 47 and a discharge means or conduit 48leading to a quenching means 49 for directing a Ljet of oil, or Yotherdielectric uid, at the'contacts 17 and 23 as they break to extinguish orquench any arc formed therebetween, as hereinafter described in moredetail. The solenoid valve 43 is provided with a passage 53 which, inone position of the valve, connects the conduit 42 to the conduit 47,and, in another position of thevalve, connects the conduit 42 to thedischarge conduit 4S. The function performed by the solenoid valve willbe discussed hereinafter when considering the operation of the'cir'cuitbreaker of the invention.

v The conduits 41 and 47 communicate with a conduit 56 leading to anaccumulator 57. The latter may be of any suitable type, the particulartype shown being equipped with a bladder 58 which is lled with nitrogen,or other suitable gas, which is compressed by the oil, or otheroperating fluid, when the system is under pressure, the gas expanding tomaintain system pressure in response to a tendency for the pressure todrop, all as will be discussed in more detail hereinafter.

Communicating with the conduits 41, 47 and 56 is a conduit 61 whichleads to the discharge side of a pump 62 through a reverse-ow-preventingcheck valve 63 and a pressure relief valve 64. The intake side of thepump 62 is connected, by a conduit 65, to a reservoir 66 containing oil,or other dielectric lluid. An overow or return conduit 70 communicatesbetween the reservoir 66 and the interior of the insulator section 7 ata level well above the contacts 17 and 23 to maintain the fluid levelwithin the insulator section 7 at the level indicated by the d numeral71. Thus, the contacts 17 and 23 are c'onstantly immersed in oil.

A pressure gauge 72 and a pressure sensitive switch 73 communicate withthe discharge side of the pump 62 by being connected in the conduit 41.The switch 73 is connected to the pressure relief valve 64, whichbypasses fluid from the pump 62 to the reservoir`66 by way of a conduit74 and the overow conduit 70 in the event 'of the development of anexcessive pressure.

Considering the operation of the invention as thus far described, aslong as no overload exists, the solenoid valve 43 is in the positionshown in Fig. l of the drawings so as to maintain the conduit 42 incommunication with the discharge side of the pump through the conduits47 and 61. Under such conditions, the same operating fluid pressure isapplied to both the small area 36 and the large area`37 of the'piston 35with the result that the contacts 17 and 2.3 are maintained inengagement. Also,

A. under such conditions, the accumulator 57 is energized, the gaswithin the bladder 58 being compressed.

When the solenoid valve 43 is actuated by the control means 44, as uponthe occurrence of an overload in the external circuit to which theterminals 9 and 11 are connected, the solenoid valve connects theconduit 42 to the discharge conduit 48. This has the elect of reducingthe pressure in the cylinder 34 on the large-area side of the piston 35to a low value equal only to the head of uid thereabove. Consequently,since the systern pressure is still applied to the small area 36 of thepiston 35, the contact 23 is disengaged from the contact 17, an adequatesupply of iiuid under pressure to insure separation of the contacts at ahigh rate. of speed being provided by the accumulator 57. Thus, a highrate of contact separation to minimize arcing is attained withoutcomplex linkage systems, or the like, which is a feature of theinvention.

The uiddisplaced by the piston 35 during movement of the piston in thecontact-opening or contact-breaking direction flows through the solenoidvalve 43 into the discharge conduit 4S and thence to the quenching means49 to quench any arc that may be formed between the separating contacts,such jets assisting in extinguishing the arc as is well known in theart. Any tendency for the tluid level 71 to rise Vas a result of theintroduction of fluid `into lthe insulator section 7 in the foregoingmanner is prevented by the overow or return conduit 70.

Considering the structure of the quenching means 49, it includes a stackof annular elements S0 having interspersed therebetween pairs ofcrescent-shaped spacers S1 providing'radial'passages 82each of whichcommunicates at one end with an inlet port 83 and at its other end withan outlet port 34. These ports are formed in the tubular insulator 15and the inlet port 83 communicates with the upper end of the dischargepassage 48, the outlet port communicating with the interior of theinsulator section 7. The quenching means 49 encirclesthe piston rod 24so that jets of oil are directed through the passages SZbetween theinlet and outlet ports 83 and 84 and around'the rod 24, when the rod isin a position such that it projects entirely through the quenching means49. As the rod 24 is moved downwardly during contacto'pening movement ofthe piston 35, successive jets of oil traversing the passages 82traverse the space between the contacts 17 and 23 to provide a pluralityof arc quenching jets of oil between the separating contacts, thenumberY of jets of oil increasing as the rod 24 is moved downwardly.Eachjet .of 'oil traversing one of the passages 82` tends to blowthe'arc into the corresponding passage 82 in the direction of the outletport84, blowing the arc into each passage 82 in this manner beingextremely eiective in quenching the arc. VUsually, the arc is completelyquenched by the time the Contact 23 has cleared one or two of thepassages 82.

In Fig. 4 of the drawings is shown in quenching means 87 which issimilar to the quenching means 49, the only diierence being that thedischarge passage 48, instead of communicating with the port 83,communicates with the upper end of the stationary contact or socket 17through the cap 14. With the quenchingV means 87, a stream of oil owsdownwardly through the contact 17 and impinges on the contact 23, theoil stream being discharged through the passages 82 radially in bothdirections toward the ports 83 and S4, both of these ports being outletports with this construction. The quenching action is similar to thatpreviously described and it is thought'that a detailed descriptionthereof is unnecessary.

Although we have disclosed exemplary embodiments of our invention hereinfor purposes of illustration, it will be understood that variouschanges, modications and substitutions may be incorporated in suchembodiments without Y'departing from the spirit of the invention asdefilled by the claims appearing hereinafter.

We claim as our invention:

1. ln a circuit breaker, the combination of: a pair of contacts;duid-operated means connected to one of said contacts for maintainingsaid contacts in engagement, said fluid-operated means being reversibleto break the engagement between said contacts, said uid-operated meansincluding a cylinder having therein a differentialarea piston connectedto said one contact, said piston having a small area facing in thedirection of contactclosing movement of said piston and having a largearea facing in the opposite direction so that said duid-operated meansmaintains said contacts in engagement when equal operating Huidpressures are applied to both of said areas of said piston; controlmeans for reversing said fluid-operated means, said control meansincluding means for reducing the operating fluid pressure applied tosaid large area of said piston so as to reverse said Huid-operatedmeans; a source of operating uid under pressure in constantcommunication with said small area of said piston; and passage means forconducting spent operating fluid `from the large-area side of saidpiston to said contacts upon reversal of said fluid-operated means so asto quench any arc formed between sai-d contacts upon breaking thereof.

2. In a circuit breaker, the combination of: a pair of contacts;duid-operated means connected to one of said contacts for maintainingsaid contacts in engagement, said duid-operated means being reversibleto break the engagement between said contacts, said iiuid-operated meansincluding a cylinder having therein a differential-area piston connectedto said one contact, said piston having a small area facing in thedirection of contactclosing movement of said piston and having a largearea facing in the opposite direction so that said duid-operated meansmaintains said contacts in engagement when equal operating uid pressuresare applied to lboth of said areas of said piston; control means forreversing said duid-operated means, said control means including meansfor reducing the operating fluid pressure applied to said large area ofsaid piston so as to reverse said fluid-operated means; and a source ofoperating fluid under pressure in constant communication with said smallarea of said piston, said source including an accumulator.

3. In a circuit breaker, the combination of: a pair of contacts;Huid-operated means for making and breaking said contacts, including acylinder having a piston therein and including a piston rod connected toone side of said piston and to one of said contacts, the presence 6 ofsaid piston rod reducing the area of said side of said piston to asmaller value than that of the opposite side of said piston; a source ofoperating iiuid under pressure; a first conduit connecting said sourceto said cylinder on the small-area side of said piston; a second conduitconnecting said source to said cylinder on the large-area side of saidpiston; a discharge means; and a control valve in said second conduitfor interrupting fluid communication between said source and saidcylinder and for connecting said cylinder on the large-area side of saidpiston to said discharge means, said discharge means comprising passagemeans leading to said contacts so as to quench any arc formed betweensaid contacts upon breaking thereof.

4. A circuit breaker as defined in claim 3 wherein said source includesa pump and an accumulator.

5. A circuit breaker as defined in claim 4 including a reservoircommunicating with the intake side of said pump and including aquenching chamber surrounding said contacts, there being a returnconduit communicating with said quenching chamber, at a level above saidcontacts, and said reservoir.

6. A circuit breaker as defined in claim 3 including a stack of annularelements having interspersed therebetween pairs of spacers providingdiametral passages communicating with said passage means and spacedapart along the path of separation of said contacts.

7. An arc quenching device including a stack of annular elements havinginterspersed therebetween pairs of crescent-shaped spacers providingdiametral passages spaced along the path of separation of a pair ofcontacts, and including means for owing a fluid through said passages.

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